Laser guided bomb with proximity sensor

ABSTRACT

A proximity sensor for a Laser Guided Bomb (LGB) is provided. A proximity sensor for a Laser Guided Bomb (LGB) includes: an electronics package unit (EPU) configured to be connected to a front end of a warhead; and at least one sensor separate from the EPU and configured to be connected to a forward adapter that is connected to the front end of the warhead. The at least one sensor is configured to obtain data that is used to determine a height above ground of the LGB. The EPU is configured to compare the determined height above ground to a predefined value. The EPU is configured to generate a detonation signal for the warhead based on the determined height above ground being equal to or less than the predefined value.

FIELD OF THE INVENTION

The present invention relates generally to air-dropped weapons andproximity (height of burst or target detection) sensors. Moreparticularly, the present invention relates to systems and methods forenabling proximity detection on Laser Guided Bombs (LGBs) and novelplacement of Radio Frequency (RF) or Electro-Optical (EO) sensorsproviding increased warhead performance.

BACKGROUND

Traditionally, LGBs are used to guide conventional general-purpose,multi-effect or penetrator warheads against point surface or sub-surfacetargets. The impact of the warhead with the target or ground initiatesthe fuze installed in the warhead, causing instantaneous or delayeddetonation of the warhead depending on the fuze setting.

There are limitations with the traditional method of employing LGBs.While extremely effective against stationary point surface orsub-surface targets such as stationary vehicles, large ships, buildings,shelters or bunkers, it is less effective against fast moving vehicles,smaller, more maneuverable watercraft or area targets such as troopsentrenched or in an open field. This is due, in part, to the degradationof accuracy of the weapon against moving targets combined with asignificant portion of the blast and fragmentation of the warhead beingabsorbed by the ground at impact, effectively reducing the probabilityof disabling or destroying the intended target. This, then necessitatesthat the pilot or aircrew either reattack the target or to carry a mixof different weapons to address multiple types of targets. Neithersituation is optimal in a theater of operations, where reducing exposureto hostile fire is vital to aircrew and aircraft survivability. Thus, itwould be desirable to provide a system that enables the LGB to detonatethe warhead prior to impact with the ground, in order to maximize theblast and fragmentation effects of the warhead against these types oftargets without requiring modification of the guidance and controlsection hardware and/or software/firmware of the LGB itself.

No conventional system provides both laser guidance and airburstcapability for a dumb-bomb, while also avoiding the use of complexInertial Navigation System (INS) and Global Positioning System (GPS)guidance systems. For example, Paveway II is a conventional bolt-on kitfor converting an unguided bomb (e.g., a dumb-bomb) to a LGB. WhilePaveway II provides laser guidance, it does not have airburstcapability.

More specifically, Paveway II kits attach to a variety of warheads, andinclude a computer control group (CCG) containing a laser detector(e.g., a semi-active laser (SAL) seeker), a computer section containingguidance and control electronics, thermal battery, and a controlactuation system (CAS). There are moveable front control canards andfixed rear wings for stability. The weapon guides on reflected laserenergy: the seeker detects the reflected light (“sparkle”) of thedesignating laser, and actuates the canards to guide the bomb toward thedesignated point. Paveway II uses only laser guidance for guiding thebomb, and does not utilize INS/GPS guidance. Paveway II also does notinclude a data interface to the launch platform. For example, sincePaveway II does not utilize GPS, there is no need for PavewayII-equipped munitions to receive any position data, velocity vectors,and target coordinates from the aircraft.

Enhanced Paveway II and Paveway IV (later versions of Paveway) are dualmode INS/GPS and laser-guided bomb kits that are based on an EnhancedComputer Control Group (ECCG). The newer ECCG in Enhanced Paveway II andPaveway IV can contain a Height of Burst (HOB) sensor enabling air burstfuzing options, and a SAASM (Selective Availability Anti SpoofingModule) compliant GPS receiver. As such, Enhanced Paveway II and PavewayIV provide both laser guidance and airburst capability, but with thedrawback of increased cost and complexity due to the ECCG and INS/GPSguidance.

The Joint Direct Attack Munition (JDAM) is another conventional bolt-onguidance kit, that converts unguided munitions (i.e., dumb bombs) intoguided munitions. By adding a tail section containing INS/GPS guidanceto existing munitions, JDAM provides highly accurate delivery in anyflyable weather. Guidance is provided by a JDAM through a tail controlsystem and INS/GPS system. The INS, using updates from the GPS, guidesthe bomb to the target via the use of movable tail fins. The navigationsystem is initialized by transfer alignment from the aircraft thatprovides position and velocity vectors from the aircraft systems. Oncereleased from the aircraft, the JDAM autonomously navigates to thedesignated target coordinates. Target coordinates can be loaded into theaircraft before takeoff, manually altered by the aircrew in flight priorto weapon release, or entered by a datalink from onboard targetingequipment.

A basic JDAM tail kit does not include laser guidance or airburst.However, these capabilities can be added to a JDAM with additionalcomponents. For example, a Laser JDAM (LJDAM) adds a laser seeker to thenose of a JDAM-equipped warhead, giving the ability to engage movingtargets to the JDAM. The laser seeker is called Precision Laser GuidanceSet (PLGS) and consists of the laser seeker itself, known as a DSU-38,installed on the nose of the warhead and a wire harness fixed under thewarhead body to connect the DSU-38 with the JDAM tail kit. Anotherupgrade to the basic JDAM system is a DSU-33, which is a radar proximitysensor that provides a HOB fire pulse signal to the fuze forJDAM-equipped warheads. The DSU-33, like the DSU-38, is designed to beinstalled in the nose well of a warhead. As such, a JDAM-equippedwarhead can only be equipped with one, but not both, of a DSU-33 and aDSU-38.

The DSU-38 is specifically designed to operate with the JDAM kit and isnot compatible with a Paveway II kit. The DSU-33 can be used on awarhead without a Paveway II kit to provide airburst capability to anunguided bomb. However, the DSU-33 cannot be used on a warhead that isequipped with a Paveway II kit. This is because a DSU-33 and theguidance kit for Paveway II both occupy the same place on the warheadsuch that attaching one to a warhead means that you cannot attach theother to the same warhead.

SUMMARY

In a first aspect of the invention, there is a proximity sensor for aLaser Guided Bomb (LGB), comprising: an electronics package unit (EPU)configured to be connected to a front end of a warhead; and at least onesensor separate from the EPU and configured to be connected to a forwardadapter that is connected to the front end of the warhead. The at leastone sensor is configured to obtain data that is used to determine aheight above ground of the LGB. The EPU is configured to compare thedetermined height above ground to a predefined value. The EPU isconfigured to generate a detonation signal for the warhead based on thedetermined height above ground being equal to or less than thepredefined value.

In another aspect of the invention, there is a guidance kit for a LaserGuided Bomb (LGB), comprising: a forward adapter configured to connectto a retainer bolt at a front end of a warhead; a computer control group(CCG) configured to connect to the forward adapter, the CCG comprising alaser detector and a computer section configured to control moveablefront control canards; and a proximity sensor comprising: at least onesensor on the forward adapter; and electronics package unit (EPU)configured to be inside the retainer bolt. The at least one sensor isconfigured to obtain data that is used to determine a height aboveground of the LGB. The EPU is configured to compare the determinedheight above ground to a predefined value. The EPU is configured togenerate a detonation signal for the warhead based on the determinedheight above ground being equal to or less than the predefined value.

In another aspect of the invention, there is a method of assembling aLaser Guided Bomb (LGB), comprising: connecting a retainer bolt to afront end of a warhead; connecting a forward adapter to the retainerbolt using a clamp ring; connecting first wiring from an electronicspackage unit (EPU) of a proximity sensor to an initiator in the warhead;connecting the EPU to the retainer bolt; and connecting second wiringfrom the EPU to at least one sensor element of the proximity sensormounted on the forward adapter.

An embodiment of the present invention is directed to a proximity sensorfor implementation on-board a LGB system guidance kit to warheadadapter, said proximity sensor including: a single or multipletransmitting/receiving antenna(s), the antenna(s) being conformal ornon-conformal to the attachment location; an electronics assembly, theassembly being connected to the antenna(s) by cabling, and containingsignal processing electronics (if not incorporated or directly connectedto the antenna(s)), power supply and management, programming switchesand associated electronics; and a cable that connects to the fuzingapparatus installed in the warhead in order to provide the detonationsignal to the fuze. The programming switches can be internal to theadapter, e.g., on the electronics assembly, or can be external to theadapter, e.g., arranged at or on an outer surface of the adapter.

An additional embodiment of the present invention is directed toproximity sensor for implementation on-board a LGB system guidance kitto warhead adapter, said proximity sensor including: a single ormultiple transmitting/receiving electro-optical (EO) device(s), the EOdevice(s) being conformal or non-conformal to the attachment location;an electronics assembly, the assembly being connected to the EOdevice(s) by cabling, and containing signal processing electronics (ifnot incorporated or directly connected to the EO device(s)), powersupply and management, programming switches and associated electronics;and a cable that connects to the fuzing apparatus installed in thewarhead in order to provide the detonation signal to the fuze.

An additional embodiment of the present invention is directed to ahybrid proximity sensor for implementation on-board a LGB systemguidance kit to warhead adapter, said hybrid proximity sensor including:a single or multiple transmitting/receiving electro-optical (EO)device(s), the EO device(s) being conformal or non-conformal to theattachment location; a single or multiple transmitting/receivingantenna(s), the antenna(s) being conformal or non-conformal to theattachment location: an electronics assembly, the assembly beingconnected to the EO device(s) and antenna(s) by cabling, and containingsignal processing electronics (if not incorporated or directly connectedto the EO device(s) and/or antenna(s)), power supply and management,programming switches and associated electronics; and a cable thatconnects to the fuzing apparatus installed in the warhead in order toprovide the detonation signal to the fuze.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present invention is described in the detailed description whichfollows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention.

FIGS. 1 and 2 show a conventional laser guided bomb.

FIG. 3 shows a laser guided bomb in accordance with aspects of theinvention.

FIG. 4 shows an arrangement of components within a warhead in accordancewith aspects of the invention.

FIG. 5 depicts a system for mounting a proximity sensor to a warhead inaccordance with aspects of the invention.

FIG. 6 depicts another system for mounting a proximity sensor to awarhead in accordance with aspects of the invention.

FIGS. 7A and 7B show mountings of sensors on a forward adapter inaccordance with aspects of the invention.

FIGS. 8A, 8B, 8C, 8D, and 8E show arrangements for mounting sensors on aforward adapter in accordance with aspects of the invention.

FIG. 9 shows an implementation of a proximity sensor in accordance withaspects of the invention.

FIG. 10 shows another implementation of a proximity sensor in accordancewith aspects of the invention.

FIGS. 11A, 11B, and 11C show aspects of a proximity sensor in accordancewith aspects of the invention.

DETAILED DESCRIPTION

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present invention onlyand are presented in the cause of providing what is believed to be themost useful and readily understood description of the principles andconceptual aspects of the present invention. In this regard, no attemptis made to show structural details of the present invention in moredetail than is necessary for the fundamental understanding of thepresent invention, the description taken with the drawings makingapparent to those skilled in the art how the several forms of thepresent invention may be embodied in practice.

The present invention relates generally to air-dropped weapons andproximity (height of burst or target detection) sensors. Moreparticularly, the present invention relates to systems and methods forenabling proximity detection on Laser Guided Bombs (LGBs) and novelplacement of Radio Frequency (RF) or Electro-Optical (EO) sensorsproviding increased warhead performance. In accordance with aspects ofthe invention, a proximity sensor is configured to provide airburstcapability to a LGB. In a preferred embodiment, the proximity sensor isparticularly configured for use with a Paveway II kit. In embodiments,the proximity sensor is independent of the laser guidance system of theLGB. In this manner, implementations of the invention provide airburstcapability to a LGB without requiring the extra complexity (and cost) ofa INS/GPS guidance system, and without requiring modification of analready existing laser guidance system.

As used herein, a Laser Guided Bomb (LGB) is a bomb that is equippedonly with a laser guidance system and is not equipped with a INS/GPSguidance system, excluding Dual Mode Laser Guided Bombs (DMLGB). Forexample, a Paveway II equipped bomb would be considered a LGB because itis equipped only with the laser guidance system of the CCG and does notutilize INS/GPS guidance. Conversely, an enhanced Paveway II and aPaveway IV equipped bomb would not be considered a LGB because each isequipped with both laser guidance and a INS/GPS guidance system (each isa DMLGB). Similarly, a Laser JDAM (LJDAM) would not be considered a LGBbecause it is equipped with both laser guidance and a INS/GPS guidancesystem.

FIGS. 1 and 2 show a conventional LGB 10. As shown in FIGS. 1 and 2, theLGB 10 includes a warhead 11, a tail assembly 12, a forward adapter 13,and a CCG 14, e.g., similar to a Paveway II equipped bomb such as aGBU-12. The forward adapter 13 is used to mount the CCG 14 to nose ofthe warhead 11 and to provide an aerodynamic transition (e.g., afairing) between the CCG 14 and the warhead 11, which may be ofdifferent diameters depending on warhead type and weight. There can bedifferently sized forward adapters 13 for differently sized warheads 11,however the function and implementation is the same for each and thustransparent to this invention.

Still referring to FIGS. 1 and 2, the CCG 14 includes a laser detector15, a computer section 16, and a control actuation system (CAS) 19 formoving the moveable front control canards 17. The laser detector 15detects reflected light of a designating laser. Based on the angle ofincidence of the detected light, the computer section 16 causes the CASto actuate (e.g., deflect) the front control canards 17 to guide the LGB10 toward the designated point. Unlike the canards 17, the wings of thetail assembly 12 remain in a fixed position after being deployed and arenot controlled by the computer section 16.

As seen in FIG. 1, the CCG 14 is attached to the forward portion (e.g.,the front end) of the warhead 11 (via the forward adapter 13) in orderto improve accuracy of the warhead using laser guidance after release ofthe LGB 10 from a launching platform such as an aircraft. The locationof the CCG 14 poses a problem for integrating a HOB (e.g., airburst)system on the LGB 10 since HOB systems typically require hardware thatalso occupies or attaches to the forward portion of the warhead.However, by modifying the forward adapter of an LGB as described herein,HOB functionality can be provided to an LGB without requiring removal ormodification of the laser guidance kit hardware.

FIG. 3 shows a LGB 20 in accordance with aspects of the invention, theLGB 20 including a warhead 11, a tail assembly 12, a forward adapter13′, and a CCG 14 similar to the LGB 10 of FIG. 1. In embodiments, theLGB 20 includes a proximity sensor 25 comprising at least one sensor 30mounted on the forward adapter 13′ and a sensor electronics package unit(EPU) 35 mounted at the nose of the warhead 11. According to aspects ofthe invention, the proximity sensor 25 is configured to determine aheight above ground of the LGB 20, and to transmit a detonation signal(e.g., a fire pulse) to a fuze system when the determined height aboveground equals or is less than a predefined value. Upon receiving thedetonation signal from the proximity sensor 25, the fuze systemdetonates the warhead 11. In this manner, the proximity sensor 25provides HOB (e.g., airburst) capability to the LGB 20.

The proximity sensor 25 may utilize any conventional or later developedtechnology that is configured to obtain data that is used to determine aheight above ground of the LGB 20. For example, the at least one sensor30 may comprise at least one Radio Frequency (RF) sensor, at least oneElectro-Optical (EO) sensor, or a combination of at least one RF sensorand at least one EO sensor. In embodiments, the EPU 35 compriseselectronics that receive data from the at least one sensor 30 andcompare the data to a predefined value. The data may be unprocesseddata, in which case the EPU 35 uses signal processing to determine aheight above ground of the LGB 20 based on the unprocessed data.Alternatively, the at least one sensor 30 may perform the signalprocessing, such that the data received by the EPU 35 arrives in theform of the determined height above ground of the LGB 20. In eitherimplementation, the EPU 35 is configured to compare the determinedheight above ground of the LGB 20 to a predefined value, and to transmita fire pulse to the fuze system when the determined height above groundof the LGB 20 is less than or equal to the predefined value. The EPU 35may comprise a computer memory for storing the predefined value and atleast one of a computer processor, FPGA, and ASIC for comparing thedetermined height above ground to the predefined value.

In an exemplary embodiment, the proximity sensor 25 utilizes an RF radaraltimeter to determine the height above ground of the LGB 20. Forexample, the at least one sensor 30 may comprise a plurality of RFantennas mounted at an exterior surface of the forward adapter 13′ andwired to the EPU 35 as described in greater detail herein. The EPU 35may include a signal generator and a signal processor that employconventional radar techniques to generate signals that are transmittedby the RF antennas and to determine a height above ground of the LGB 20based on reflected signals received by the RF antennas. Implementationsof the invention are not limited to this example, and the proximitysensor 25 may utilize other techniques (e.g., Electro-Optical distancemeasuring techniques) to determine the height above ground of the LGB20.

After the LGB 20 is launched from a platform (e.g., dropped from anaircraft), the height above ground of the LGB 20 constantly changes asthe LGB 20 falls through the air. Accordingly, the proximity sensor 25is configured to repeat the detecting (by the at least one sensor 30)and the comparing (by the EPU 35) until such a time as the determinedheight above ground of the LGB 20 is less than or equal to thepredefined value. The proximity sensor 25 may be configured to repeatthe detecting and the comparing at any desired interval, including butnot limited to once per millisecond, to provide a desired accuracy ofthe HOB function.

In accordance with aspects of the invention, the proximity sensor 25determines the height above ground of the LGB 20 independent of thelaser guidance system of the CCG 14. For example, in determining theheight above ground of the LGB 20, the proximity sensor 25 utilizes dataobtained only by the at least one sensor 30, and does not utilize datafrom the laser detector 15 and/or the computer section 16. In thismanner, the proximity sensor 25 operates independently of the CCG 14and, thus, does not require modification of, or connection to, the CCG14. In this manner, implementations may be used with a conventionalPaveway II without requiring any modification of, or connection to, theCCG of the conventional Paveway II.

FIG. 4 diagrammatically depicts an exemplary arrangement of elements ofthe system in the warhead 11 of the LGB 20 of FIG. 3. The warhead 11 maybe a conventional warhead including but not limited to an Mk-82, Mk-83,or Mk-84. As shown in FIG. 4, the warhead 11 includes a body 39 that hasa forward fuze well 40, a charging well 42, and an aft fuze well 44.Lugs 45 are provided on the exterior of the body 39 for connecting thewarhead 11 to an aircraft in a conventional manner. An interior of thebody 39 may include an amount of explosive material 50 that can bedetonated by a fuze to cause the warhead 11 to explode.

In embodiments, the EPU 35 is mounted in or forward of the forward fuzewell 40, an initiator 46 is mounted in the charging well 42, and a fuze48 is mounted in the aft fuze well 44. The fuze system may comprise theinitiator 46 and the fuze 48. In embodiments, the EPU 35 sends adetonation signal (e.g., a fire pulse) to the fuze 48 via the initiator46. Upon receiving the fire pulse from the initiator 46, the fuze 48detonates the explosive material 50 contained inside the body 39 of thewarhead 11. The initiator 46 may comprise but is not limited to an FZUor Mk-122 switch. The fuze 48 may comprise but is not limited to anFMU-139 or an FMU-152 fuze.

As shown in FIG. 4, first cabling 61 (e.g., wiring inside a conduit) maybe provided inside the body 39 to operatively connect the EPU 35 and theinitiator 46, such that the EPU 35 can transmit the fire pulse to theinitiator 46 via the first cabling 61. Second cabling 62 (e.g., wiringinside a conduit) may be provided inside the body 39 to operativelyconnect the initiator 46 and the fuze 48, such that the initiator 46 cantransmit the fire pulse to the fuze 48 via the second cabling 62.

FIG. 4 also diagrammatically depicts the forward adapter 13′ connectedto the forward end of the warhead 11. In embodiments, the at least onesensor 30 mounted on the forward adapter 13′ and is operativelyconnected to the EPU 35 by cabling 70 (e.g., wiring) as describedherein. In a preferred embodiment, the forward adapter 13′ is a PavewayII forward adapter that is modified with the at least one sensor 30mounted thereon. Although not shown in FIG. 4, a CCG of a Paveway II maybe connected to the forward adapter 13′ and a Paveway II tail assembly12 may be attached to the tail end of the warhead 11 (e.g., as depictedin FIG. 3).

FIG. 5 depicts a system for mounting a proximity sensor to a warhead inaccordance with aspects of the invention. As shown in FIG. 5, an aft endof a retainer bolt 80 has a threaded exterior surface 82 that isconfigured to be threadingly connected to a threaded interior surface ofthe forward fuze well 40 of the warhead 11. An o-ring may be providedbetween the retainer bolt 80 and the warhead 11, and a setscrew may bethreaded through a bore in the body 39 of warhead 11 to urge against thethreaded exterior surface 82 of the retainer bolt 80 to prevent theretainer bolt 80 from backing out of threaded connection with thewarhead 11. In embodiments, the EPU 35 has a threaded exterior surface84 that is configured to be threadingly connected to a threaded interiorsurface 86 of the retainer bolt 80. The forward adapter 13′ isconfigured to be mounted on the retainer bolt 80 by moving the forwardadapter 13′ in the direction indicated by arrow “A” until an internalcircular flange 88 of the forward adapter 13′ abuts against an externalcircular flange 90 of the retainer bolt 80. With the forward adapter 13′thus mounted on the retainer bolt 80, a clamp ring 92 having an threadedinterior surface 94 is threadingly connected to a threaded exteriorsurface 96 at the forward end of the retainer bolt 80. A setscrew may bethreaded through a bore in the clamp ring 92 to urge against theinternal circular flange 88 of the forward adapter 13′ to prevent theretainer clamp ring 92 from backing out of threaded connection with theretainer bolt 80. When the LGB 20 is assembled in this manner, the EPU35 is secured to the front end of the warhead 11 and covered by theforward adapter 13′.

In the embodiment shown in FIG. 5, the EPU 35 does not extend into theforward fuze well 40. Accordingly, a support cup 97 or other structuraldevice may be placed in the forward fuze well 40, e.g., forstrengthening the LGB 20 for penetrating hardened targets. The supportcup 97 may comprise, for example, a steel cylinder having a wallthickness in a range of ¼ inch to ½ inch, for example.

FIG. 6 depicts another system for mounting a proximity sensor to awarhead in accordance with aspects of the invention. The arrangementshown in FIG. 6 includes the same forward adapter 13′, retainer bolt 80,and clamp ring 92 as described with respect to FIG. 5. The retainingbolt 80 is mounted to the warhead 11 in the same manner as describedwith respect to FIG. 5. The EPU 35′ is inserted through the retainerbolt 80 and partially into the forward fuze well 40 of the warhead 11. Afuze retaining nut 98 with a threaded exterior surface 100 is configuredto be threadingly connected to the threaded interior surface 86 of theretaining bolt 80 to hold the EPU 35′ in place relative to the retainingbolt 80 (i.e., in the forward fuze well 40). After connecting the fuzeretaining nut 98, the forward adapter 13′ and the clamp ring 92 areconnected in the same manner as described with respect to FIG. 5. In theembodiment shown in FIG. 6, the EPU 35′ is longer than the EPU 35 ofFIG. 5 such that the EPU 35′ extends at least partially into the forwardfuze well 40 of the warhead 11. In embodiments, the EPU 35′ may beconstructed of material of sufficient strength and thickness toapproximate a conventional support cup that is used for strengthening abomb for penetrating hardened targets. For example, the EPU 35′ may havean outer cylindrical wall 102 that is composed of steel having athickness in a range of ¼ inch to ½ inch.

Although not shown in FIGS. 5 and 6, it is to be understood that duringinstallation of the EPU 35 (or EPU 35′), wiring may be connected betweenthe EPU 35 (or EPU 35′) and the initiator 46 via the first cabling 61 asshown in FIG. 4. Also during installation of the EPU 35 (or EPU 35′),wiring may be connected between the EPU 35 (or EPU 35′) and the at leastone sensor element 30 via the cabling 70 as shown in FIG. 4.

FIGS. 7A and 7B show mountings of sensors on a forward adapter inaccordance with aspects of the invention. In an exemplary embodimentdepicted in FIG. 7A, the at least one sensor 30 of the proximity sensor25 includes at least two antennas 30 a and 30 b mounted on an outersurface 110 of the forward adapter 13′. The antennas 30 a and 30 b maybe, for example, patch antennas that are connected to the outer surface110 by any suitable technique including but not limited to adhesive,mechanical fastener (e.g., screw, nut and bolt, rivet, etc.), or acombination of adhesive and mechanical fastener. In a preferredembodiment the antennas 30 a and 30 b are RF patch antennas that formpart of an RF radar altimeter of the proximity sensor 25.

In the embodiment shown in FIG. 7A, the antennas 30 a and 30 b aremounted on a shroud portion 112 of the forward adapter 13′ which is aftof a dividing line 114 that delineates a structural portion 116 and theshroud portion 112. However, the antennas 30 a and 30 b are not limitedto mounting on the shroud portion 112 and instead may be mounted at anydesired location(s) on the outer surface 110 of the forward adapter 13′.Any desired number ‘n’ of antennas 30 a-n may be mounted on the outersurface 110 of the forward adapter 13′.

Still referring to FIG. 7A, the antennas 30 a and 30 b may beoperatively connected to the EPU 35 (not shown) by cabling 70 (e.g.,electrical wiring). A portion of the cabling 70 may extend along theouter surface 110 of the forward adapter 13′, pass through a bore 118 inthe outer surface 110 of the forward adapter 13′, and extend from thebore 118 to the EPU 35. Alternatively, the cabling 70 may extend fromthe antennas 30 a and 30 b directly through a bore 118 in the outersurface 110 of the forward adapter 13′ without extending along the outersurface 110 of the forward adapter 13′ (e.g., as depicted in FIG. 8B).In a preferred embodiment, the antennas 30 a and 30 b are mounted on theshroud portion 112 of the forward adapter 13′ and the bore 118 is in thestructural portion 116 of the forward adapter 13′, with the cabling 70running along the outer surface 110 of the forward adapter 13′ from theantennas 30 a and 30 b to respective bores 118. In this manner, thestructural modification of the forward adapter 13′ (e.g., the bores 118)is made at the structural portion 116.

In an exemplary embodiment depicted in FIG. 7B, the at least one sensor30 of the proximity sensor 25 includes at least two conformal antennas30 a′ and 30 b′ mounted on the outer surface 110 of the forward adapter13′. The conformal antennas 30 a′ and 30 b′ may be connected to theouter surface 110 by any suitable technique including but not limited toadhesive, mechanical fastener (e.g., screw, nut and bolt, rivet, etc.),or a combination of adhesive and mechanical fastener. In a preferredembodiment the conformal antennas 30 a′ and 30 b′ are RF antennas thatform part of an RF radar altimeter of the proximity sensor 25.

In the embodiment shown in FIG. 7B, the conformal antennas 30 a′ and 30b′ are mounted on the structural portion 116 of the forward adapter 13′which is forward of the dividing line 114 that delineates the structuralportion 116 and the shroud portion 112. However, the conformal antennas30 a and 30 b are not limited to mounting on the structural portion 116and instead may be mounted at any desired location(s) on the outersurface 110 of the forward adapter 13′. Any desired number ‘n’ ofconformal antennas 30 a′-n′ may be mounted on the outer surface 110 ofthe forward adapter 13′.

Similar to the embodiment described with respect to FIG. 7A, theconformal antennas 30 a′ and 30 b′ may be connected to the EPU 35 viacabling 70. The cabling may extend along the outer surface 110 of theforward adapter 13′, pass through a bore in the outer surface 110 of theforward adapter 13′, and extend from the bore to the EPU 35.Alternatively, the cabling 70 may extend from the conformal antennas 30a′ and 30 b′ directly through a bore in the outer surface 110 of theforward adapter 13′ without extending along the outer surface 110 of theforward adapter 13′ (e.g., as depicted in FIG. 8B).

FIGS. 8A, 8B, 8C, and 8D show arrangements for mounting sensors on aforward adapter in accordance with aspects of the invention. FIG. 8Aillustrates an arrangement in which an antenna (e.g., antenna 30 a) ismounted on the outer surface 110 of the forward adapter 13′ such thatthe antenna protrudes outward from the outer surface 110. FIG. 8Billustrates an arrangement in which an antenna (e.g., antenna 30 a) ismounted in a recessed portion of the outer surface 110 of the forwardadapter 13′ such that the outer surface of the antenna is flush with theouter surface 110. FIG. 8B also illustrates the cabling 70 extendingdirectly from the antenna 30 a through the bore 118 without extendingalong the outer surface 110. FIG. 8C illustrates an arrangement in whichan antenna (e.g., 30 a) is mounted in a through-hole in the forwardadapter 13′ such that an outer surface of the antenna is flush with theouter surface 110. FIG. 8D illustrates an arrangement in which anantenna (e.g., 30 a) is mounted on the outer surface 110 of the forwardadapter 13′ such that the antenna protrudes outward from the outersurface 110, with the cabling 70 extending directly from the antenna 30a through the bore 118 without extending along the outer surface 110. Inthe manner shown in FIGS. 8A-8D, at least one sensor (e.g., 30 a) isconfigured to be at an outer surface of the forward adapter 13′. Themounting arrangements shown in FIGS. 8A-8D can be used with theimplementation shown in FIG. 7A or the implementation shown in FIG. 7B.As used herein, flush carries the meaning of the term that would beunderstood by those of skill in the art and may include reasonabletolerances that are understood by those of skill in the art.

FIG. 8E shows an exemplary embodiment of an antenna and cablingarrangement in accordance with aspects of the invention. FIG. 8Ediagrammatically shows a cross section of the forward adapter 13′ withthe EPU 35, and omits other elements (such as the retainer ring) forclarity. As shown in FIG. 8E, the antenna 30 a is mounted through athrough-hole in the shroud portion 112 of the forward adapter 13′, suchthat the outer surface of the antenna 30 a is flush with the outersurface 110 of the shroud portion 112 of the forward adapter 13′. Thecabling 70 that connects the antenna 30 a to the EPU 35 extends from theantenna 30 a to an interior of the shroud portion 112, through a bore inthe shroud portion 112, along the outer surface 110 from a location atthe shroud portion 112 to a location at the structural portion 116,through a bore in the structural portion 116, and in the interior of thestructural portion to the EPU 35. A cover 120 may be arranged on theouter surface 110 of the forward adapter 13′ to cover the portion of thecabling 70 that runs along the outer surface 110. Although a singleantenna 30 a is shown, it is understood that any suitable number ofantennas may be used, including but not limited to four antennas evenlyspaced around the circumference of the forward adapter 13′.

Although FIGS. 7A-7B and 8A-8E are described with respect to RFantennas, implementations of the invention are not limited to RF sensorsand instead may employ other types of sensors. For example, the elements30 a and 30 b (or 30 a′ and 30 b′) may alternatively represent EOsensors or a combination of RF and EO sensors.

FIGS. 9 and 10 show implementations of a proximity sensor in accordancewith aspects of the invention. In embodiments, the proximity sensor 25is configured to permit manual adjustment of at least one of airburstheight and arming time. In a first embodiment, shown in FIG. 9, the EPU35 includes a height switch 130 that permits manual adjustment of HOB(airburst) height and an arm time switch 132 that permits manualadjustment of arming time of the proximity sensor 25.

The height switch 130 may be any type of switch that permits manualadjustment by a human user to select one value from a plurality ofpredefined values for an airburst height for the LGB 20. In theembodiment shown in FIG. 9, the height switch 130 is a dial that has tenpredefined locations corresponding to ten respective airburst heights(e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 meters). A user may manually adjustthe airburst height of the LGB 20 by turning the dial to one of the tenpredefined locations.

In accordance with aspects of the invention, the EPU 35 compriseselectronics that detect the airburst height selected by a user via theheight switch 130 and that use this selected airburst height as thepredefined value that is compared against the determined height aboveground of the LGB 20. For example, if the user adjusts the height switch130 to a setting of 10 meters, then the EPU 35 sends the detonationsignal (e.g., a fire pulse) to the fuze 48 via the initiator 46 when theEPU 35 determines that the determined height above ground of the LGB 20equals or is less than 10 meters. In this manner, the height switch 130is used to selectively set an above ground altitude at which the warheadwill detonate, such that the proximity sensor 25 provides an adjustableHOB function to the LGB 20.

The height switch 130 is not limited to the number of predefinedlocations shown in FIG. 9 (e.g., ten predefined locations). Instead, theheight switch 130 may have any number of predefined locations greaterthan one. Moreover, the proximity sensor 25 is not limited to the heightvalues shown in FIG. 9 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 meters).Instead, the EPU 35 may be programmed with any desired heights for therespective predefined locations of the height switch 130. As but onealternate example, the height switch 130 may have six predefinedlocations with respective height values of 10, 15, 20, 25, 30, 35 feet.Other configurations may be used within the scope of the invention. Theheight switch 130 is not limited to a single switch. Instead, pluralswitches may be configured to provide an operator that ability toselectively set an above ground altitude at which the warhead willdetonate. For example, the height switch 130 may comprise two switches:a first switch configured to set a tens of feet value, with predefinedvalues including integers from zero to nine; and a second switchconfigured to set a ones of feet value, with predefined values includingintegers from zero to nine. In this manner, the two switches may be usedto set a value from one to 99 feet in increments of one foot.

Still referring to FIG. 9, the arm time switch 132 is a switch thatpermits manual adjustment of arming time of the proximity sensor 25. Inembodiments, the arming time is a time that the proximity sensor 25waits before ‘turning on’ after the LGB 20 has detached from theairplane (e.g., a time that the proximity sensor waits before beginningthe processes of determining the height above ground of the LGB 20 andcomparing of the determined height above ground to the predefinedvalue). The arm time switch 132 may be any type of switch that permitsmanual adjustment by a human user to select one value from a pluralityof predefined values for the arming time of the proximity sensor 25. Inthe embodiment shown in FIG. 9, the arm time switch 132 is a dial thathas five predefined locations corresponding to five respective armingtimes (e.g., 10, 15, 20, 25, 30 seconds). A user may manually adjust thearming time of the proximity sensor 25 by turning the dial to one of thefive predefined locations.

The arming time is a wait time that is triggered by the LGB 20 beinglaunched (e.g., detaching) from the airplane. In embodiments, theinitiator 46 selectively provides an enable signal (e.g., a voltage) tothe EPU 35 based on the LGB 20 detaching from the airplane. For example,the initiator 46 may comprise, or be configured similar to, aconventional FZU or Mk- 122 that begins generating a voltage essentiallyinstantaneously after detaching from the airplane. A conventionalinitiator provides this voltage to the fuze to arm the fuze. In aspectsof the invention, the initiator 46 supplies this voltage to both thefuze 48 and the EPU 35 (e.g., via the cabling 61 and 62 shown in FIG.4). In embodiments, the EPU 35 is configured to ‘turn on’ a predefinedamount of time after receiving this voltage from the initiator 46. Inembodiments, the EPU 35 comprises electronics that detect the armingtime selected via the arm time switch 132, and the EPU 35 uses theselected arming time as the predefined amount of time to wait before‘turning on’ after receiving the voltage from the initiator 46. Forexample, if the arm time switch 132 is set to the 20 seconds position,then the EPU 35 will ‘turn on’ 20 seconds after receiving the voltagefrom the initiator 46 (which is essentially 20 seconds after the LGB 20detaches from the airplane). In this manner, implementations of theinvention provide for manual adjustment of an arming time of theproximity sensor 25

The arm time switch 132 is not limited to the number of predefinedlocations shown in FIG. 9 (e.g., five predefined locations). Instead,the arm time switch 132 may have any number of predefined locationsgreater than one. Moreover, the proximity sensor 25 is not limited tothe arming time values shown in FIG. 9 (e.g., 10, 15, 20, 25, 30seconds). Instead, the EPU 35 may be programmed with any desired armingtimes for the respective predefined locations of the arm time switch132.

FIG. 10 shows another implementation of a proximity sensor in accordancewith aspects of the invention. In the exemplary implementation shown inFIG. 9, the height switch 130 and the arm time switch 132 are arrangedon the EPU 35, e.g., on a front face of the EPU 35. In the exemplaryimplementation shown in FIG. 10, the height switch 130′ and the arm timeswitch 132′ are arranged remote from the EPU 35, e.g., on the outersurface 110 of the forward adapter 13′. In embodiments, the heightswitch 130′ and the arm time switch 132′ are configured to operate inthe same manner and to provide the same functionality as the heightswitch 130 and the arm time switch 132 as described with respect to FIG.9. The height switch 130′ and the arm time switch 132′ may be wired tothe EPU 35, e.g., in a manner similar to how the antennas 30 a and 30 bare wired to the EPU 35. Mounting the height switch 130′ and the armtime switch 132′ on the outer surface 110 of the forward adapter 13′advantageously permits a user to inspect and/or adjust one or both ofthe switches after the LGB 20 is fully assembled, e.g., after theforward control kit 14 is connected to the forward adapter 13′. In thismanner, implementations of the invention provide a mechanism for manualadjustment of at least one of the airburst height and the arming time ofthe LGB 20 after the LGB 20 is fully assembled.

In embodiments, the EPU 35 comprises a safety enable switch that permitsselectively enabling and disabling the proximity sensor. FIGS. 11A-Cillustrate aspects of an ON/OFF control of the proximity sensor 25 usingthe safety enable switch in accordance with aspects of the invention.FIG. 11A diagrammatically depicts the LGB 20 attached to a rack 138 onan airplane 140. FIGS. 11B and 11C diagrammatically depict the LGB 20falling away from the rack 138 after detaching from the rack 138. Forclarity, only the EPU 35 is shown in FIGS. 11A-C, but it is understoodthat the LGB 20 depicted in FIGS. 11A-C is a fully assembled LGB 20 suchas that shown in FIG. 3.

As shown in FIG. 11A, the LGB 20 is attached to the rack 138 prior tobeing launched (e.g., dropped). The rack 138 may comprise any suitablerack including but not limited to a BRU-32 ejector rack. In embodiments,a lanyard 142 has a first end connected to the rack 138 and a second endconnected to a safety enable switch 144 of the EPU 35 of the LGB 20. Thefirst end of the lanyard 142 is connected to a portion of the rack 138that is configured to selectively retain or release the first end of thelanyard 142. For example, the first end of the lanyard 142 may beattached to a zero retention force (ZRF) solenoid switch 146 included inthe rack 138. FIG. 11B depicts the situation in which the solenoidswitch 146 retains the lanyard 142 when the LGB 20 is launched, and FIG.11C depicts the situation in which the solenoid switch 146 releases thelanyard 142 when the LGB 20 is launched.

In accordance with aspects of the invention, the safety enable switch144 has a default state of OFF, and is configured to be switched ON bythe lanyard 142 exerting a force on the safety enable switch 144 whenthe LGB 20 drops from the rack 138 as depicted in FIG. 11B. Stateddifferently, when the LGB 20 drops from the rack 138 and the lanyard 142is retained by the rack 138, the lanyard 142 pulls against the safetyenable switch 144 and throws the safety enable switch 144 to the ONposition. Conversely, when the LGB 20 drops from the rack 138 and thelanyard 142 is released by the rack 138 (e.g., as depicted in FIG. 11C),the safety enable switch 144 remains in the OFF position because thelanyard 142 does not exert sufficient force on the safety enable switch144 to throw the switch.

In embodiments, the EPU 35 is configured such that the proximity sensor25 only ‘turns on’ when two conditions are satisfied: (i) the EPU 35receives the enable signal from the initiator 46 (as described withrespect to FIG. 9) and (ii) the safety enable switch 144 is ON. If bothconditions are satisfied and an arming time has been selected using thearm time switch 132, then the EPU 35 will turn on after receiving theenable signal from the initiator 46 and waiting the amount of time setby the arm time switch 132. Conversely, when the safety enable switch144 is OFF, the proximity sensor 25 will not turn ON despite receivingthe enable signal from the initiator 46. The LGB 20 does not have HOB(airburst) capability when the proximity sensor 25 is OFF. As such,controlling the solenoid switch 146 to retain or release the lanyard 142can be used to cause the HOB capability of the launched LGB 20 to be ONor OFF. In embodiments, the solenoid switch 146 may be controlled usingconventional techniques, e.g., based on crewmember input at the cockpitof the airplane. In this manner, an ON/OFF state of the HOBfunctionality of the LGB 20 may be selectively controlled by acrewmember in flight, even though the LGB 20 does not have an electronicdata/communications interface with the airplane 140.

According to aspects of the invention, the combination of thecontrollable ON/OFF state provided by the safety enable switch 144, theairburst height provided by the height switch 130, and a programmabledelay of the fuze 48 provides the ability for the aircrew to change theLGB 20 from an airburst bomb to a delayed detonation (e.g., penetrating)bomb in flight, and without utilizing an electronic data/communicationsinterface between the airplane 140 and the LGB 20.

An exemplary use case illustrates this functionality. In this example,the fuze 48 is programmed with a delay of 25 milliseconds, such that thefuze 48 is configured to detonate the warhead at a time of 25milliseconds after either (i) the fuze 48 receiving the fire pulse fromthe initiator 46 or (ii) the fuze 48 detecting impact (e.g., with theground). In this example, the proximity sensor 25 is programmed with anairburst height greater than a distance the LGB 20 is expected to travelduring the fuze delay. In this example, a human operator manipulates theheight switch 130 to select an airburst height of 35 ft. Accordingly, ifthe proximity sensor 25 is turned ON when the LGB 20 is launched (e.g.,as described using the lanyard 142 and safety enable switch 144), thenthe proximity sensor 25 will generate the a detonation signal when theLGB 20 is 35 ft above ground. The fuze 48 will receive the detonationsignal and wait a time of 25 milliseconds and then initiate detonationof the warhead. An LGB 20 typically travels at a terminal velocity ofabout 1000 feet/second (or 1 foot/millisecond). As such, the LGB 20travels about 25 feet during the 25 millisecond fuze delay and thenexplodes at an altitude of 10 feet (i.e., 35 feet minus 25 feet) aboveground, thus acting as an airburst bomb. Conversely, if the proximitysensor 25 is turned OFF when the LGB 20 is launched (e.g., as describedusing the lanyard 142 and safety enable switch 144), then the proximitysensor 25 will not generate a detonation signal at all (even though theheight switch 130 is set to 35 feet). In this situation, the LGB 20falls until impact (e.g., with the ground) and the fuze 48 detonates thewarhead 25 milliseconds after the impact, thus acting as a delayeddetonation/penetrating bomb. In this manner, the safety enable switch144 can be used in flight to control the LGB 20 to be either an airburstbomb or a delayed detonation/penetrating bomb.

It is noted that the foregoing examples have been provided merely forthe purpose of explanation and are in no way to be construed as limitingof the present invention. While the present invention has been describedwith reference to an exemplary embodiment, it is understood that thewords which have been used herein are words of description andillustration, rather than words of limitation. Changes may be made,within the purview of the appended claims, as presently stated and asamended, without departing from the scope and spirit of the presentinvention in its aspects. Although the present invention has beendescribed herein with reference to particular means, materials andembodiments, the present invention is not intended to be limited to theparticulars disclosed herein; rather, the present invention extends toall functionally equivalent structures, methods and uses, such as arewithin the scope of the appended claims.

What is claimed:
 1. A proximity sensor for a Laser Guided Bomb (LGB),comprising: an electronics package unit (EPU) configured to be connectedto a front end of a warhead; and at least one sensor separate from theEPU and configured to be connected to a forward adapter that isconnected to the front end of the warhead; wherein the at least onesensor is configured to obtain data that is used to determine a heightabove ground of the LGB; the EPU is configured to compare the determinedheight above ground to a predefined value; and the EPU is configured togenerate a detonation signal for the warhead based on the determinedheight above ground being equal to or less than the predefined value. 2.The proximity sensor of claim 1, wherein the EPU comprises a cylindricalpackage configured to fit inside a retainer bolt that is connected tothe front end of the warhead.
 3. The proximity sensor of claim 2,wherein the EPU comprises a threaded exterior surface that is configuredto be threadingly connected to a threaded interior surface of theretainer bolt.
 4. The proximity sensor of claim 1, wherein the at leastone sensor is configured to be at an outer surface of the forwardadapter.
 5. The proximity sensor of claim 4, further comprising cablingthat operatively connects the at least one sensor to the EPU.
 6. Theproximity sensor of claim 5, wherein the cabling extends through a borein the forward adapter.
 7. The proximity sensor of claim 6, wherein theat least one sensor is configured to be on a shroud portion of theforward adapter and the bore is in a structural portion of the forwardadapter.
 8. The proximity sensor of claim 1, wherein the proximitysensor comprises: a height switch that permits manual adjustment of thepredefined value; and an arm time switch that permits manual adjustmentof arming time.
 9. The proximity sensor of claim 8, wherein the heightswitch and the arm time switch are on the EPU.
 10. The proximity sensorof claim 1, wherein the EPU comprises a safety enable switch thatpermits selectively enabling and disabling the proximity sensor.
 11. Theproximity sensor of claim 1, wherein the forward adapter is a Paveway IIforward adapter that is configured to be connected to a Paveway IIforward guidance kit.
 12. A guidance kit for a Laser Guided Bomb (LGB),comprising: a forward adapter configured to connect to a retainer boltat a front end of a warhead; a computer control group (CCG) configuredto connect to the forward adapter, the CCG comprising a laser detectorand a computer section configured to control moveable front controlcanards; and a proximity sensor comprising: at least one sensor on theforward adapter; and an electronics package unit (EPU) configured to beinside the retainer bolt; wherein the at least one sensor is configuredto obtain data that is used to determine a height above ground of theLGB; the EPU is configured to compare the determined height above groundto a predefined value; and the EPU is configured to generate adetonation signal for the warhead based on the determined height aboveground being equal to or less than the predefined value.
 13. Theguidance kit of claim 12, wherein the proximity sensor comprises: aheight switch that permits manual adjustment of the predefined value;and an arm time switch that permits manual adjustment of arming time.14. The guidance kit of claim 13, wherein the height switch and the armtime switch are on the EPU.
 15. The guidance kit of claim 12, whereinthe EPU comprises a safety enable switch that permits selectivelyenabling and disabling the proximity sensor.
 16. A method of assemblinga Laser Guided Bomb (LGB), comprising: connecting a retainer bolt to afront end of a warhead; connecting a forward adapter to the retainerbolt using a clamp ring; connecting first wiring from an electronicspackage unit (EPU) of a proximity sensor to an initiator in the warhead;connecting the EPU to the retainer bolt; and connecting second wiringfrom the EPU to at least one sensor element of the proximity sensormounted on the forward adapter.
 17. The method of claim 16, furthercomprising connecting a computer control group (CCG) to the forwardadapter, wherein the CCG comprises: a laser detector, at least onemoveable front control canard, a control actuation system (CAS) thatcontrols a position of at the least one moveable front control canard,and a computer section that provides commands to the CAS to selectivelycontrol the position of the at least one moveable front control canardbased on signals from the laser detector.
 18. The method of claim 16,wherein the connecting the EPU to the retainer bolt comprisesthreadingly connecting an external threaded surface of the EPU with aninternal threaded surface of the retainer bolt.
 19. The method of claim16, wherein the connecting the EPU to the retainer bolt comprises:passing the EPU through the retainer bolt and into a forward fuze wellof the warhead; and threadingly connecting an external threaded surfaceof a fuze retaining nut with an internal threaded surface of theretainer bolt.
 20. The method of claim 16, further comprising at leastone of: manually adjusting an airburst height using a height switchconnected to the EPU; and manually adjusting an arming time using an armtime switch connected to the EPU.